Integrated circuits (ICs) are typically mounted in packages to protect the sensitive integrated circuitries from environmental influences. However, one disadvantageous side effect that may be observed is that mounting the integrated circuitry in a package exerts mechanical stress on the semiconductor material. Mechanical stress on integrated circuits changes electronic parameters, such as the magnetic sensitivity of Hall plates or the resistance of resistors. Mechanical stress changes the mobility and the scatter factor of charge carriers, which causes lifetime drifts of resistances, transistor parameters, and the magnetic sensitivity of Hall plates (known as piezo-resistivity effect, piezo-MOS effect, piezo-junction effect, and piezo-Hall effect).
Lifetime drift of mechanical stress originates from changes of the thermo-mechanical properties of the package constituents (e.g. ageing or chemical reactions in the mold compound or swelling of the mold compound due to moisture ingress), and typically cannot be avoided. Silicon Hall sensors are known to suffer from a long term drift in magnetic sensitivity between 1% and 4% depending upon the degree of moisture in the mold compound of the package.